The ACT Legislative Assembly has agreed in principal to change drugs laws relating to people found with small quantities of the chemicals used to make methamphetamine and ice.

Attorney General Simon Corbell says the changes are needed to combat the modern realities of organised crime.

"Members do need to be aware in considering this amendment, that there is an increasing trend for organised crime to spread its risk by using a large number of people to each produce small amounts of illegal drugs rather than getting one person to manufacture a large quantity."

But Greens MLA Shane Rattenbury is concerned the legislation would see people charged with trafficking a drug even if it is for personal use.

"A good example would be a young teenager decides to experiment by going onto the internet, getting a recipe, having the ingredients and then turning those into tablets," he said.

"It [the law] now presumes that they're going to sell them which means that person would now be liable for a dealing offence or trafficking offence instead of just simply a possession offence."